Preparation And Properties Of Sustained Release Microsphere Based On Emulsion Solvent Evaporation Method

Objective: To prepare the Aspirin PEG-PLGA sustained- release microspheres and puerarin sustained-release microspheres by emulsion solvent evaporation method for experimential basic of innovative pharmaceutics research and development. Methods: The first part, the preparation and pharmaceutic characterization of aspirin sustained- release microspheres:(1) to explore the optimal polymer materials;(2) and then investigate the preparation of microsphere. The microspheres were characterized by different techniques as following: scanning electron microscopy(SEM), laser particle size analyzer, differential scanning calorimetry(DSC), X-ray diffraction(XRD), nuclear magnetic resonance analysis(NMR), fourier transform infrared spectroscopy(FT-IR). Further, dynamic dialysis method was uesd to detect the characteristics of drug in vitro release. The second part, the preparation and pharmacy characterization of puerarin sustained – release microspheres: the optimal polymer materials and the preparation of microsphere were investiaged same as first part. The microspheres were also characterized by different techniques as following: SEM, laser particle size analyzer, thermogravimetric analysis(TGA), DSC, XRD. And the characteristics of drug release were determined in vitro. Results: The first part, aspirin microspheres: polyethylene glycol- poly(lactic acid- glycolic acid)(PEG-PLGA) was optimally selected by orthogonal test. The mean drug loading of the microspheres, encapsulation efficiency, and average particle size was(5.74±1.93) %,(97.77±2.83) %,(100.9±2.52) μm of prepared with DCM: ACE, respecitively. However, the mean drug loading of the microspheres, encapsulation efficiency, and average particle size was(10.67±1.78) %,(98.10±1.74) %,(142.4 ± 3.25) μm of prepared with DCM: EA, respecitively. The surface of two groups of aspirin PEG-PLGA microsphere were smooth and round with very few adhesions observed by SEM.The microspheres were not undergoing a simple physical mixing of the two substances with DSC and XRD analysis. In addition, NMR and IR analysis confirmed that aspirin was not combine with PEG-PLGA on the main functional groups. In vitro, 95% cumulative release of microspheres was 120 h and 168 h prepared with DCM: ACE and DCM: EA, respectively. The second part, the preparation and pharmacy characterization of puerarin sustained – release microspheres: the optimum polymer material was poly L-lactic acid(PLA). The surface of puerarin microsphere prepared with optimal prescription was smooth, round, and no adhesions.The drug loading, encapsulation efficiency, yield, average particle size was(26.20±2.24) %,(68.92±1.88) %,(83.97±2.55) %,(104.3±0.13) μm, respectively. The results of TGA, DSC, and XRD were clarified the changes in the physical form of molecular spatial relationship of the copolymer and drug in microsphere, the drug may be in an amorphous state dispersed in the carrier material. In vitro, 60 % cumulative release of the puerarin PLA microspheres(Pue-PLA-MSs) was 1320 h. Conclusion: Two sustained- release microspheres of aspirin and puerarin were successfully prepared by emulsion solvent evaporation method. The microspheres have professional properities as following: high drug loading, encapsulation efficiency, and excellent sustained release function. And the optimal process was simple and reasonable, which is base for further research.